From the Guidelines
For a 22-year-old female presenting with 3-4 months of hair thinning and loss, the recommended initial laboratory tests should include complete blood count (CBC), thyroid-stimulating hormone (TSH), ferritin, vitamin D level, and a comprehensive metabolic panel. Additionally, testing for hormonal imbalances with total and free testosterone, dehydroepiandrosterone sulfate (DHEAS), and sex hormone-binding globulin (SHBG) is important, as suggested by 1. These tests help identify common causes of hair loss in young women such as iron deficiency anemia, thyroid dysfunction, nutritional deficiencies, and hormonal disorders like polycystic ovary syndrome (PCOS). Ferritin levels should ideally be above 50 ng/mL for optimal hair growth, as iron is essential for hair follicle function, although the evidence for this is not entirely consistent, as seen in 1. Thyroid disorders can significantly impact hair growth cycles, while vitamin D deficiency has been linked to various forms of hair loss, as indicated by studies such as 1. Hormonal testing is particularly relevant as androgen excess can lead to androgenetic alopecia. If autoimmune conditions are suspected, antinuclear antibodies (ANA) might also be considered. These laboratory evaluations should be performed alongside a thorough clinical history that includes medication use, recent stressors, family history, and a physical examination of the scalp and hair loss pattern. Key considerations include:
- Iron deficiency, which is a common cause of hair loss and can be assessed through serum ferritin levels 1
- Thyroid dysfunction, which can impact hair growth and should be evaluated with TSH levels 1
- Vitamin D deficiency, which has been linked to hair loss and can be assessed through serum vitamin D levels 1
- Hormonal imbalances, particularly androgen excess, which can lead to androgenetic alopecia and should be evaluated with tests such as total and free testosterone, DHEAS, and SHBG 1
From the Research
Initial Laboratory Tests for Hair Thinning and Loss
The initial laboratory tests for a 22-year-old female presenting with 3-4 months of hair thinning and loss may include:
- Complete Blood Count (CBC) to check for anemia and other blood-related disorders 2, 3
- Serum ferritin to assess iron stores, as decreased serum ferritin is associated with alopecia in women 2, 4
- Vitamin B12 levels, as its deficiency could be a probable cause of iron deficiency, especially in vegetarians 3
- Thyroid function tests, including TSH, to rule out hypothyroidism, which may be associated with androgenic hair loss 2, 5
- Vitamin D levels, as deficiencies in vitamins and minerals may play a role in developing, preventing, and treating nonscarring alopecia 2
Rationale for Test Selection
The selection of these tests is based on the findings of various studies, including:
- A study published in the Turkish Journal of Medical Sciences, which found that ferritin, hemoglobin, and vitamin B12 levels were significantly lower in patients with telogen effluvium compared to other groups 2
- A study published in Dermatology Research and Practice, which found that stress, topical application of chemicals, and systemic medications were common exacerbating factors for acquired alopecia in females, and that thyroid disorders were not statistically significant 3
- A study published in The Journal of Investigative Dermatology, which found that decreased serum ferritin is associated with alopecia in women, particularly those with androgenetic alopecia and alopecia areata 4